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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.] */
#include <openssl/bn.h>
#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <openssl/bio.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "internal.h"
BIGNUM *BN_bin2bn(const uint8_t *in, size_t len, BIGNUM *ret) {
unsigned num_words, m;
BN_ULONG word = 0;
BIGNUM *bn = NULL;
if (ret == NULL) {
ret = bn = BN_new();
}
if (ret == NULL) {
return NULL;
}
if (len == 0) {
ret->top = 0;
return ret;
}
num_words = ((len - 1) / BN_BYTES) + 1;
m = (len - 1) % BN_BYTES;
if (bn_wexpand(ret, num_words) == NULL) {
if (bn) {
BN_free(bn);
}
return NULL;
}
ret->top = num_words;
ret->neg = 0;
while (len--) {
word = (word << 8) | *(in++);
if (m-- == 0) {
ret->d[--num_words] = word;
word = 0;
m = BN_BYTES - 1;
}
}
/* need to call this due to clear byte at top if avoiding having the top bit
* set (-ve number) */
bn_correct_top(ret);
return ret;
}
size_t BN_bn2bin(const BIGNUM *in, uint8_t *out) {
size_t n, i;
BN_ULONG l;
n = i = BN_num_bytes(in);
while (i--) {
l = in->d[i / BN_BYTES];
*(out++) = (unsigned char)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return n;
}
/* constant_time_select_ulong returns |x| if |v| is 1 and |y| if |v| is 0. Its
* behavior is undefined if |v| takes any other value. */
static BN_ULONG constant_time_select_ulong(int v, BN_ULONG x, BN_ULONG y) {
BN_ULONG mask = v;
mask--;
return (~mask & x) | (mask & y);
}
/* constant_time_le_size_t returns 1 if |x| <= |y| and 0 otherwise. |x| and |y|
* must not have their MSBs set. */
static int constant_time_le_size_t(size_t x, size_t y) {
return ((x - y - 1) >> (sizeof(size_t) * 8 - 1)) & 1;
}
/* read_word_padded returns the |i|'th word of |in|, if it is not out of
* bounds. Otherwise, it returns 0. It does so without branches on the size of
* |in|, however it necessarily does not have the same memory access pattern. If
* the access would be out of bounds, it reads the last word of |in|. |in| must
* not be zero. */
static BN_ULONG read_word_padded(const BIGNUM *in, size_t i) {
/* Read |in->d[i]| if valid. Otherwise, read the last word. */
BN_ULONG l = in->d[constant_time_select_ulong(
constant_time_le_size_t(in->dmax, i), in->dmax - 1, i)];
/* Clamp to zero if above |d->top|. */
return constant_time_select_ulong(constant_time_le_size_t(in->top, i), 0, l);
}
int BN_bn2bin_padded(uint8_t *out, size_t len, const BIGNUM *in) {
size_t i;
BN_ULONG l;
/* Special case for |in| = 0. Just branch as the probability is negligible. */
if (BN_is_zero(in)) {
memset(out, 0, len);
return 1;
}
/* Check if the integer is too big. This case can exit early in non-constant
* time. */
if ((size_t)in->top > (len + (BN_BYTES - 1)) / BN_BYTES) {
return 0;
}
if ((len % BN_BYTES) != 0) {
l = read_word_padded(in, len / BN_BYTES);
if (l >> (8 * (len % BN_BYTES)) != 0) {
return 0;
}
}
/* Write the bytes out one by one. Serialization is done without branching on
* the bits of |in| or on |in->top|, but if the routine would otherwise read
* out of bounds, the memory access pattern can't be fixed. However, for an
* RSA key of size a multiple of the word size, the probability of BN_BYTES
* leading zero octets is low.
*
* See Falko Stenzke, "Manger's Attack revisited", ICICS 2010. */
i = len;
while (i--) {
l = read_word_padded(in, i / BN_BYTES);
*(out++) = (uint8_t)(l >> (8 * (i % BN_BYTES))) & 0xff;
}
return 1;
}
static const char hextable[] = "0123456789abcdef";
char *BN_bn2hex(const BIGNUM *bn) {
int i, j, v, z = 0;
char *buf;
char *p;
buf = (char *)OPENSSL_malloc(bn->top * BN_BYTES * 2 + 2);
if (buf == NULL) {
OPENSSL_PUT_ERROR(BN, BN_bn2hex, ERR_R_MALLOC_FAILURE);
return NULL;
}
p = buf;
if (bn->neg) {
*(p++) = '-';
}
if (BN_is_zero(bn)) {
*(p++) = '0';
}
for (i = bn->top - 1; i >= 0; i--) {
for (j = BN_BITS2 - 8; j >= 0; j -= 8) {
/* strip leading zeros */
v = ((int)(bn->d[i] >> (long)j)) & 0xff;
if (z || v != 0) {
*(p++) = hextable[v >> 4];
*(p++) = hextable[v & 0x0f];
z = 1;
}
}
}
*p = '\0';
return buf;
}
/* decode_hex decodes |i| bytes of hex data from |in| and updates |bn|. */
static void decode_hex(BIGNUM *bn, const char *in, int i) {
int h, m, j, k, c;
BN_ULONG l=0;
j = i; /* least significant 'hex' */
h = 0;
while (j > 0) {
m = ((BN_BYTES * 2) <= j) ? (BN_BYTES * 2) : j;
l = 0;
for (;;) {
c = in[j - m];
if ((c >= '0') && (c <= '9')) {
k = c - '0';
} else if ((c >= 'a') && (c <= 'f')) {
k = c - 'a' + 10;
} else if ((c >= 'A') && (c <= 'F')) {
k = c - 'A' + 10;
} else {
k = 0; /* paranoia */
}
l = (l << 4) | k;
if (--m <= 0) {
bn->d[h++] = l;
break;
}
}
j -= (BN_BYTES * 2);
}
bn->top = h;
}
/* decode_dec decodes |in_len| bytes of decimal data from |in| and updates |bn|. */
static void decode_dec(BIGNUM *bn, const char *in, int in_len) {
int i, j;
BN_ULONG l = 0;
j = BN_DEC_NUM - (in_len % BN_DEC_NUM);
if (j == BN_DEC_NUM) {
j = 0;
}
l = 0;
for (i = 0; i < in_len; i++) {
l *= 10;
l += in[i] - '0';
if (++j == BN_DEC_NUM) {
BN_mul_word(bn, BN_DEC_CONV);
BN_add_word(bn, l);
l = 0;
j = 0;
}
}
}
typedef void (*decode_func) (BIGNUM *bn, const char *in, int i);
typedef int (*char_test_func) (int c);
static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_func want_char) {
BIGNUM *ret = NULL;
int neg = 0, i;
int num;
if (in == NULL || *in == 0) {
return 0;
}
if (*in == '-') {
neg = 1;
in++;
}
for (i = 0; want_char((unsigned char)in[i]); i++) {}
num = i + neg;
if (outp == NULL) {
return num;
}
/* in is the start of the hex digits, and it is 'i' long */
if (*outp == NULL) {
ret = BN_new();
if (ret == NULL) {
return 0;
}
} else {
ret = *outp;
BN_zero(ret);
}
/* i is the number of hex digests; */
if (bn_expand(ret, i * 4) == NULL) {
goto err;
}
decode(ret, in, i);
bn_correct_top(ret);
if (!BN_is_zero(ret)) {
ret->neg = neg;
}
*outp = ret;
return num;
err:
if (*outp == NULL) {
BN_free(ret);
}
return 0;
}
int BN_hex2bn(BIGNUM **outp, const char *in) {
return bn_x2bn(outp, in, decode_hex, isxdigit);
}
char *BN_bn2dec(const BIGNUM *a) {
/* It is easier to print strings little-endian, so we assemble it in reverse
* and fix at the end. */
BIGNUM *copy = NULL;
CBB cbb;
if (!CBB_init(&cbb, 16) ||
!CBB_add_u8(&cbb, 0 /* trailing NUL */)) {
goto cbb_err;
}
if (BN_is_zero(a)) {
if (!CBB_add_u8(&cbb, '0')) {
goto cbb_err;
}
} else {
copy = BN_dup(a);
if (copy == NULL) {
goto err;
}
while (!BN_is_zero(copy)) {
BN_ULONG word = BN_div_word(copy, BN_DEC_CONV);
if (word == (BN_ULONG)-1) {
goto err;
}
const int add_leading_zeros = !BN_is_zero(copy);
int i;
for (i = 0; i < BN_DEC_NUM && (add_leading_zeros || word != 0); i++) {
if (!CBB_add_u8(&cbb, '0' + word % 10)) {
goto cbb_err;
}
word /= 10;
}
assert(word == 0);
}
}
if (BN_is_negative(a) &&
!CBB_add_u8(&cbb, '-')) {
goto cbb_err;
}
uint8_t *data;
size_t len;
if (!CBB_finish(&cbb, &data, &len)) {
goto cbb_err;
}
/* Reverse the buffer. */
size_t i;
for (i = 0; i < len/2; i++) {
uint8_t tmp = data[i];
data[i] = data[len - 1 - i];
data[len - 1 - i] = tmp;
}
BN_free(copy);
return (char *)data;
cbb_err:
OPENSSL_PUT_ERROR(BN, BN_bn2dec, ERR_R_MALLOC_FAILURE);
err:
BN_free(copy);
CBB_cleanup(&cbb);
return NULL;
}
int BN_dec2bn(BIGNUM **outp, const char *in) {
return bn_x2bn(outp, in, decode_dec, isdigit);
}
int BN_asc2bn(BIGNUM **outp, const char *in) {
const char *const orig_in = in;
if (*in == '-') {
in++;
}
if (in[0] == '0' && (in[1] == 'X' || in[1] == 'x')) {
if (!BN_hex2bn(outp, in+2)) {
return 0;
}
} else {
if (!BN_dec2bn(outp, in)) {
return 0;
}
}
if (*orig_in == '-' && !BN_is_zero(*outp)) {
(*outp)->neg = 1;
}
return 1;
}
int BN_print(BIO *bp, const BIGNUM *a) {
int i, j, v, z = 0;
int ret = 0;
if (a->neg && BIO_write(bp, "-", 1) != 1) {
goto end;
}
if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1) {
goto end;
}
for (i = a->top - 1; i >= 0; i--) {
for (j = BN_BITS2 - 4; j >= 0; j -= 4) {
/* strip leading zeros */
v = ((int)(a->d[i] >> (long)j)) & 0x0f;
if (z || v != 0) {
if (BIO_write(bp, &hextable[v], 1) != 1) {
goto end;
}
z = 1;
}
}
}
ret = 1;
end:
return ret;
}
int BN_print_fp(FILE *fp, const BIGNUM *a) {
BIO *b;
int ret;
b = BIO_new(BIO_s_file());
if (b == NULL) {
return 0;
}
BIO_set_fp(b, fp, BIO_NOCLOSE);
ret = BN_print(b, a);
BIO_free(b);
return ret;
}
BN_ULONG BN_get_word(const BIGNUM *bn) {
switch (bn->top) {
case 0:
return 0;
case 1:
return bn->d[0];
default:
return BN_MASK2;
}
}